I'm not a catamaran designer, but wouldn't it be easy to put four wheel mounts on the keel and then drag it up on land if there's a sudden need for repair? You could use a truck or a winch with a sturdy tree. This could drastically lower maintenance costs. I'm thinking that the wheels wouldn't be mounted when the boat is in the water, only when there's a need to bring it ashore. There could be four structurally reinforced holes where an axle can be placed. The bearings can be placed between the wheels and the axle. So when the need arises, you could use a snorkel or scuba gear, insert the axle into the existing holes on the keel, attach the wheels, and then drag it ashore. Many marinas usually have a paved ramp, but if the wheels are big enough, maybe a beach would work just as well. Many catamarans can already be beached with the help of the tide and stand on their keels. This wouldn't be much different.
